>>
>>Mark writes:
>>
>
>>50-100 lp/mm is typical for _on-film_ resolution. Aerial resolution,
>>which could be measured by focusing the lens on a resolution target
>>and looking at the back of hte lens with a microscope and focusing
>>the microscoe on the aerial image produced by the lens, is always
>>much higher. Today's optics for 35mm have aerial resolution
>>well past 100 lp/mm. It is film that limits them to 50-100 lp/mm,
>>not diffraction (up to f/11). Even if you had a lens with a
>>500 lp/mm aerial resolution, it probably would only resolve around
>>150 lp/mm on film, if even that.
>>
>>The diffraction limits are limits on the aerial resolution, not the
>>on-film resolution.
>
>
>I hadn't heard of this before.
>
>If you are limited by the film to be about 100 lp/mm resolution when
>in fact most 35mm lenses are far above this, then why are ANY lenses
>quoted in having less than 100 lp/mm resolution. Look at some of
>the numbers in the web pages linked to Lee Hawkins web site. Some
>lenses, wide open, are down around 50 lp/mm. This doesn't seem to
>make sense.
>
>
>Mark H.
>
Thank you, Mark. And in the light of the usual published resolution by
Fuji, for Velvia for instance, of 160 lines per millimeter, it makes even
less sense.
Winsor
Winsor Crosby
Long Beach, California
mailto:wincros@xxxxxxxxxxx
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